Point of dispense heat exchanger for fluids

ABSTRACT

A heat exchanger for fluids includes an elongated conduit. At least two spaced fluid passageways are defined in the conduit and extend longitudinally through the conduit from a first end thereof to a second end thereof. A heat transfer element thermally contacts a surface of the conduit to transfer heat to or from a fluid flowing through the at least two spaced passageways. The conduit can be unitary and of one piece. In one embodiment, the conduit can be a single crystal.

BACKGROUND

This application claims the benefit of Provisional Application Ser. No. 62/334,082 which was filed on May 10, 2016. The entire content of that application is incorporated hereinto by reference.

The present disclosure relates to heat exchangers. More particularly, the disclosure relates to an inline heat exchanger for fluids (the term “fluids” includes both liquids and gases). In one embodiment, the inline heat exchanger can be used to heat corrosive fluids such as are used in semiconductor manufacturing at or close to the point where such fluids are being dispensed during the manufacturing process. Because the fluids are corrosive, it is important that they be contained in conduits which can resist corrosion. For semiconductor manufacturing, it is also important that the chemicals not be contaminated during their passage through the heat exchanger.

In the manufacture of semiconductor devices, there may be several hundred cleaning and etching process steps. Over one third of these processing steps relate to wet processes. Many of the wet processes use aggressive acids, oxidizers and solvents which are raised to a high temperature and are used at high concentrations. As the geometries of the semiconductor devices get smaller and smaller, the need to control these processes employed in semiconductor manufacturing and their effectiveness becomes more and more critical. Known processes in the industry include Standard Clean 1 (SC1), Standard Clean 2 (SC2), Piranha, hydrofluoric acid (HF), hydrochloric acid (HCL) and sulfuric acid. These are just a few of the typical fluids which are employed to perform various cleaning, etching and stripping processes on the semiconductor wafer. Most, if not all, of these processes are performed at elevated temperatures. By heating the fluids to higher temperatures, they become more reactive and therefore perform the required cleaning, etching and stripping processes more effectively and efficiently. However, the use of elevated temperatures and the reactivity of the chemicals employed also degrades the fluids and thus requires more frequent replenishment of the fluids or a complete change of the fluids as these processing steps are performed.

Most of these heated chemical processes are now performed through what is known as a recirculation loop. This loop includes a storage vessel, a pump, an inline chemical heater and a filter located within the plumbing module of a wet tool employed in semiconductor manufacturing. The fluid is constantly circulated within the self-contained recirculation loop as it is heated to the desired process temperature. Once the entire volume of fluid is at the desired process temperature, it is distributed to the processing chamber or tank to either produce a single semiconductor wafer or a batch of wafers at a time. The wafer is then typically rinsed with the deionized water many times at elevated temperatures. This can be followed by a drying process which can employ several methods. One of these methods involves the use of the solvent isopropyl alcohol (IPA) which is held at an elevated temperature. Another such method involves the use of nitrogen gas and a point of dispense heater can also be employed or utilized to heat the gas.

The heating of bulk solutions and then distributing the solutions to where they are needed (which can be termed point of use or point of dispense) is energy inefficient. It is also inefficient in terms of processing time and it uses more fluids or solution due to the aforementioned degradation of the chemicals at elevated temperatures while they are not being used for the processing of wafers. It should be appreciated that many of the chemicals are expensive, costing anywhere from $150 to $1,000 per gallon and, therefore, in order to minimize costs, it would be desirable to reduce the amount of chemicals needed for the processing of such wafers. Traditional recirculation loops employ what is known as inline chemical heaters which are traditionally made from chemically inert materials, such as fluoropolymers or single crystal quartz.

As mentioned, high purity quartz has previously been used in heat exchangers for heating systems for the chemicals employed in semiconductor manufacturing. It is also known to employ metal tubing in which the corrosive fluid is held in thermoplastic tube liners so as to retard the corrosive fluid from negatively affecting the metal tubing. In this design, a flow channel is defined between the tube and the tube liner for accommodating a purge fluid which is employed to vent away any corrosive fluid which may permeate the thermoplastic tube liner. One such arrangement is discussed in U.S. Pat. No. 9,562,703 dated Feb. 7, 2017. The subject matter of that patent is incorporated hereinto by reference in its entirety.

Such known heat exchangers when used as heaters are traditionally large in mass and slow to heat the processing fluid that is continually recirculated through the heater during the initial heat up phase and throughout the processing stages to overcome heat losses, depletion of the fluids and the addition of new fluids due to the degradation of the fluids in question.

Thus, in the known systems, heaters are contained in the plumbing area of wet tools and distribution plumbing is employed to lead the heated fluid out to the fluid dispensing nozzle within the chambers or tanks where the semiconductor wafers are processed. However, this takes up a significant amount of room within these processing tools. Since such semiconductor processing takes place in a controlled environment, the room taken up by the heating assemblies for the processing fluids employed is responsible for a significant amount of the costs associated with semiconductor processing equipment. This known distribution method also incurs temperature losses due to the extended travel paths of the recirculated fluids as they travel from the heated recirculation loop to the process chamber or tank.

Therefore, it would be advantageous to eliminate the traditional recirculation loop by placing a process fluid heat exchanger as close to the processing fluid dispensing nozzle as possible. This would create a point of dispense heat exchanger and allow for the processing fluid to remain at ambient temperatures and only be raised or lowered to the required processing temperature when specifically required for processing a semiconductor wafer.

Heating or cooling the processing fluid only at the point of its dispensing or discharge would serve to minimize the footprint of the processing fluid handling and preprocessing preparation section of the plumbing area of the semiconductor tool. It would also mean that the processing fluid is no longer subjected to temperature losses, for example, as the fluid travels from a heated tank to the processing area. This would greatly simplify the cost and configuration of the processing tools and enhance their functionality. It would also save money as less processing fluid would be needed. In order to effectively achieve such a result, the heat exchanger in question must be small in size, low in mass and have a very fast response time in order to minimize the waste of processing fluid while it is either being drained or returned to a storage container such as during its initial heating phase. It would also be advantageous for the heat exchanger to accommodate a wide range of flow rates as these can vary based on the process parameters associated with the various processing steps involved in semiconductor manufacture.

BRIEF DESCRIPTION

According to one embodiment of the present disclosure, a heat exchanger assembly comprises an elongated conduit body including a first end, a second end and an outer periphery. A first fluid passage is defined in the conduit body and extends longitudinally in the conduit body from the first end thereof to the second end thereof. A second fluid passage is defined in the conduit body and extends longitudinally in the conduit body from the first end thereof to the second end thereof. The second fluid passage is spaced from and fluidically isolated from the first fluid passage. A heat transfer element is mounted to the outer periphery of the conduit body, wherein the heat transfer element thermally contacts the conduit body and is adapted to transfer heat to or from the conduit body by conduction.

A method of controlling heat transfer to a process fluid flowing in a conduit includes the steps of providing a conduit body, including a first end, a second end, an outer periphery and a longitudinal axis and defining a central bore in the conduit body, the central bore extending along the longitudinal axis from the first end of the conduit body to the second end thereof. A first process fluid passage is defined in the conduit body, the first process fluid passage extending parallel to the longitudinal axis from the first end of the conduit to the second end thereof. A second process fluid passage is defined in the conduit body, the second process fluid passage extending parallel to the longitudinal axis from the first end of the conduit body to the second end thereof, wherein the first and second process fluid passages are fluidically isolated from each other and from the central bore. The outer periphery of the conduit body is thermally contacted with a first heat transfer source. The central bore of the conduit body is thermally contacted with a second heat transfer source. A transfer of heat to the process fluid flowing through the first and second fluid passages is regulated.

According to another embodiment of the present disclosure, a unitary one-piece tubular fluid conduit for a heat exchanger comprises a first end, a second end, an outer periphery and a longitudinal axis. A first process fluid passage is defined in the conduit and extends in the conduit parallel to the longitudinal axis from the first end thereof to the second end thereof. A second process fluid passage is defined in the conduit and extends in the conduit parallel to the longitudinal axis from the first end thereof to the second end thereof. A central bore is defined in the conduit and extends along the longitudinal axis. The first and second process fluid passages are non-circular in cross section to promote a turbulent flow of the process fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure may take form in certain parts and arrangements of parts, several embodiments of which will be described in detail in this specification and illustrated in the accompanying drawings which form a part hereof and wherein:

FIG. 1 is schematic perspective view of a one-piece point of dispense heat exchanger for fluids according to a first embodiment of the present disclosure;

FIG. 2 is a perspective view of a heat exchanger according to a second embodiment of the present disclosure;

FIG. 3 is a perspective view of a heat exchanger according to a third embodiment of the present disclosure;

FIG. 4 is a perspective view of a heat exchanger according to a fourth embodiment of the present disclosure;

FIG. 5 is a perspective view of a heat exchanger according to a fifth embodiment of the present disclosure;

FIG. 6A is a perspective view of one type of end cap employing a manifold which can be coupled to a heat exchanger according to one embodiment of the present disclosure;

FIG. 6B is a perspective view of another type of end cap which can be coupled to a heat exchanger according to another embodiment of the present disclosure;

FIG. 6C is a perspective view of still another type of end cap which can be coupled to a heat exchanger according to a still further embodiment of the present disclosure;

FIG. 7 is an end elevational view of a conduit which can be used with a heat exchanger according to another embodiment of the present disclosure;

FIG. 8 is an end elevational view of a conduit which can be used with a heat exchanger according to still another embodiment of the present disclosure;

FIG. 9 is an end elevational view of a conduit which can be used with a heat exchanger according to a further embodiment of the present disclosure;

FIG. 10 is an end elevational view of a conduit which can be used as a heat exchanger according to a still further embodiment of the present disclosure;

FIG. 11 is an end elevational view of a conduit which can be used as a heat exchanger according to yet a further embodiment of the present disclosure;

FIG. 12 is an end elevational view of a conduit which can be used as a heat exchanger according to an additional embodiment of the present disclosure;

FIG. 13 is a perspective view of the conduit of FIG. 12 illustrated in use in a heat exchanger setting;

FIG. 14 is a perspective view of a conduit which can be used as a heat exchanger according to a yet still further embodiment of the present disclosure; and

FIG. 15 is a schematic view of a typical nozzle employed in the manufacture of semiconductor devices illustrating schematically where a heat exchanger according to the present disclosure may be positioned inside or secured to such a nozzle.

DETAILED DESCRIPTION

Referring now to the drawings wherein the showings are for purposes of illustrating several embodiments of the present disclosure only and not for purposes of limiting same, FIG. 1 illustrates a point of dispense heat exchanger 10 according to a first embodiment of the present disclosure. In this embodiment, the heat exchanger includes a conduit or tube 12 which is unitary and of one-piece and comprises a central passageway or bore 16 that extends longitudinally or axially into the tube from a first end of the conduit or tube. It can extend all the way to a second end thereof. Located radially outwardly from the central passageway or bore 16 are a plurality of spaced fluid paths or fluid passageways 18. It is noted that there is no fluid communication between the central passageway 16 and the several fluid paths 18. In other words, the central passageway 16 and the several fluid paths 18 are fluidically isolated from each other such that there is no fluid communication between the central passageway and the several fluid paths or fluid passages.

In one embodiment, the several fluid paths 18 also do not communicate with each other. Rather, all of these extend generally parallel to each other, are spaced from each other and extend axially (parallel to the axis of the conduit 12) from a first end of the conduit to a second end of the conduit. As mentioned, the passageway 16 and fluid paths 18 are oriented generally parallel to each other but are spaced apart. Thus, a fluid flowing in the central passageway 16 and a fluid flowing in the several fluid paths 18 does not mix in the conduit 12. In another embodiment, one or more of the fluid paths 18 could be designed to communicate with another of the fluid paths. Provided on an outer periphery 22 of the conduit 12 in this embodiment is a heating element 26.

In this embodiment, the singular or unitary or one-piece conduit or tube serves as the interface between fluid paths and a heating or cooling source. The conduit can be configured to accommodate a broad range of fluids and applications. The quantity, size, and shape of the fluid paths could all be changed based on the specific application of the heat exchange system. For example, in one embodiment, an odd number of paths are defined in the one-piece conduit or tube in order to allow for an inlet and an outlet to be located on opposing ends of the conduit. Such an embodiment is illustrated in FIG. 2. The tube or conduit can be made from a range of materials as selected in order to provide optimum heat transfer and chemical compatibility.

In one embodiment, the material comprising the tube or conduit 12 can be a single crystal sapphire material. Sapphire, particularly single crystal sapphire, is advantageous due to its high thermal conductivity, chemical resistance and other characteristics. These characteristics include physical, chemical and optical properties allowing the material to withstand high temperatures, high pressures, thermal shock and water erosion. Moreover, single crystal sapphire is chemically inert with a low friction coefficient and with excellent electrical, optical and dielectric characteristics. In addition, it is radiation resistant.

One type of such a sapphire material is a synthetic sapphire. Synthetic sapphire is a single crystal form of corundum, AL₂O₃. This is also known as alpha-alumina or alumina. Sapphire is thus an aluminum oxide in its purest form with no porosity or grain boundaries making it theoretically dense. Such synthetic sapphire material has somewhat directional heat transfer properties. With a single crystal sapphire, heat transfer is best when the respective fluid passages are aligned perpendicular to the 011 plane of the single crystal sapphire. The combination of favorable chemical, electrical, mechanical, optical, surface, thermal and durability properties make sapphire a preferred material for high performance systems and component designs. For various semiconductor applications, sapphire is considered to be the best choice when compared to other synthetic single crystals.

One known manufacturer of such single crystal synthetic sapphire materials is Kyocera Corporation of Japan. Another manufacturer is Gavish Industrial Technologies & Materials located in Omer, Israel. The manufacturer in question can provide a one-piece conduit as described above having more than one fluid passageway extending longitudinally there through. The conduit can be formed as a single crystal body of the same chemical composition having the same crystal orientation. In other words, the conduit is a unitary, one-piece body having multiple longitudinally extending fluid flow paths which are separated from one another and extend from a first end of the conduit to a second end of the conduit. It is advantageous to have a point of dispense heat exchanger contained in a single tube or conduit which contains multiple pathways that are configurable based upon process heating requirements as this allows for a low mass, fast response heater or heat exchanger which is resistant to the corrosive fluids flowing through the heat exchanger.

It should be appreciated, however, that other materials could be employed for the heat exchanger. Other materials are contemplated depending on the type of fluid being heat treated and other heat exchange parameters. Such other materials include quartz, stainless steel, titanium, aluminum, silicon carbide, silicon nitride and the like. As another possibility, it is conceivable that an electrically non-conducting and chemically resistive polymer such as polytetrafluoroethylene (PTFE) conduit could be extruded and that holes or passages could be bored through it. Alternatively, the holes could be extruded with the conduit. However, the disadvantage of PTFE and the like plastic materials is that they have a low rate of heat conduction in comparison to crystalline materials and metals. The disadvantage of an extruded metal conduit with holes bored through it or defined in it is that metal is not resistant to corrosive chemicals and it conducts electricity. It would be advantageous to provide an electrically non-conducting or isolative conduit that is resistant to corrosive chemicals and which, nevertheless, has good heat transfer capabilities so as to efficiently transfer heat to and from a process fluid flowing through fluid passages defined in the conduit. It is believed that for certain materials a 3D printing process can be used to form or manufacture the conduit, tube or heat exchanger body. It is also desirable to reduce the thermal mass of the conduit body so as to more effectively control heat transfer to the process fluid flowing in the conduit. Thus, the fluid passages defined in the conduit should be relatively large in comparison to the cross section of the conduit.

Extremely low thermal mass is quite important to the functionality of an effective point of dispense heat exchanger, such as a process fluid heater. The lower the thermal mass of the heat exchanger, the faster the heat exchanger can respond to changes in the demands of the processing requirement. Fast, controllable changes permit very accurate temperature control. This has become increasingly more critical for wet chemistry wafer processing steps. Accurate temperature control is so important that a great deal of resources and monies have been invested in its evolution. This is evident from, e.g., U.S. Pat. No. 6,178,291, entitled “Demand Anticipation Control System for a High Efficiency Ultra-Pure Fluid Heater”. The disclosure of that patent is incorporated hereinto in its entirety. The control method described in the '291 patent accounts for all thermal loads of a given process to achieve very accurate temperature control. However, a significant portion of the control is required to account for the thermal mass of the heater itself. The control scheme accounts for time and energy required to heat the heater before the heater can then itself heat the process fluid.

To achieve the lowest possible thermal mass, the heater must be designed as efficiently as possible. It is efficient from an assembly perspective to provide a one-piece unitary conduit, rather than a multiple piece body that needs to be assembled to form a single conduit. Also, a single one-piece conduit or tube allows for the heat exchanger to be more easily configured based on the process fluid which is meant to be thermally treated, i.e., heated in this embodiment, and based on the required flow rate and the required temperature rise. Because of the many types of processing fluids (wet chemistries) utilized in the production of a semiconductor device with varying thermal and physical processes, a single heat exchanger or heater design would not be effective to achieve the desired results.

Ideal thermal transfer occurs when the fluid is in contact with the heat exchange surface (the interior wall of one of the flow paths in the tube) in a turbulent state. In this state, the fluid absorbs heat from the heated surface by continually exposing the cooler fluid to the heated surface creating the largest possible thermal driving force. In laminar flow, a film of fluid is created at the heat exchange surface which film or layer then impedes the transfer of heat by effectively reducing the thermal driving force. One way of promoting a turbulent flow of the process fluid is to form the fluid passages in the conduit body as non-circular fluid passages, such as the elliptical and oval passages illustrated in several embodiments of the present disclosure.

However, since turbulent flow creates a significant pressure drop in the fluid through the system, a balance needs to be found between the level of turbulence applied to the fluid and the pressure drop of the fluid. These must be carefully engineered, creating a “figure of merit.” A “figure of merit” is a quantity used to characterize the performance of a device relative to its alternatives. It is a numerical expression representing the performance or efficiency of a given design in comparison to other designs. In the present context, figure of merit measures the ratio between the heat transfer rate and the pressure drop through the several fluid paths. Thus, for the instant application, the “figure of merit” is the ratio of improved heat transfer to pressure drop. Optimizing the “figure of merit” permits the most efficient heat exchanger for a given application.

In one embodiment, the fluid pathways can have regular shapes. In the embodiment of FIG. 1, it is apparent that the central passageway 16 is circular in cross section, whereas the several fluid paths 18 are oval or elliptical in cross section. In this embodiment, six such elliptically-shaped (in cross section) fluid paths are provided arranged radially around the centrally located passageway 16. However, the number of radial fluid passageways could vary as may be needed for a particular application. As noted above, an odd number of pathways may be provided in the tube or conduit, so as to allow for an inlet on one end and an outlet on the other end of the tube or conduit. Similarly, the shapes of the fluid passageways can be regular or irregular as may be required for a particular application. Thus, a multitude of geometries can be provided for both the central passageway and the peripheral fluid flow paths. In addition, the geometry of the conduit 12 can also be varied. In other words, its cross section need not be circular. Each of the passageways or fluid paths 16 and 18, as well as the conduit 12 can be engineered around the figure of merit. The modified oval or elliptical shape of the fluid paths 18 is such that it maximizes the heat transfer while maintaining a relatively low pressure drop.

A round tube or conduit is the most common shape for nearly all heat exchangers. Employing a round tube as the mechanical design is advantageous because it is robust for efficiently withstanding pressure and is relatively simple to produce. The difficulty with using such a round tube is that a relatively high velocity fluid flow is required in order to achieve turbulent flow. This is a good thing when distributing flow, but not ideal for efficient heat transfer. A common example of an improved design for heat transfer is an automotive radiator. In this design, the tubes are oval shaped in order to increase the amount of heat exchange area and also to improve the “figure of merit.”

It is for this reason that in one embodiment a relatively round or cylindrical tube made of a sapphire material is provided with a round central passageway 16 and elliptical or oval radial fluid flow paths 18. In other words, a plurality of freestanding fluid flow paths is defined in the conduit 12. In theory, these could also be machined or molded into the conduit when the conduit is made from one of the other listed materials. The internal fluid paths 18 would be the wetted surface with the main thermal transfer tube serving as the interface between the temperature control elements, such as the heating element 26 and the fluid which is being heated or cooled. The construction or provision of a rounded conduit 12 allows the resistance heating element 26 to be directly wound onto the outer periphery of the tube for intimate thermal contact and likely the lowest overall mass. Having a low overall mass is an advantage for the operation of a heating system.

Particularly advantageous are elliptical fluid paths integrated within the round thermal transfer conduit or tube. The shape of the fluid flow paths 18 is advantageous for the effective operation of the heat exchanger assembly. There are several attributes of this shape which impact the performance of the design. The first is that it greatly improves the available exchange area per volume when compared to round fluid paths. The second attribute is the figure of merit as discussed above.

In one embodiment, the outside and inside geometry of the conduit 12 is optimized for the interface with the heat source, in this case the electrical resistance heating element 26. The conduit can be optimized based on requirements as to heat capacity, density and viscosity of the fluid which is being thermally treated. Thus, the design of the conduit is not limited by or based on the material of the conduit. Moreover, the conduit can be configured to be employed with a manifold for a variety of fluid paths, such as parallel fluid paths, series fluid paths or a combination of the two.

With reference now to FIG. 2, according to another embodiment of the present disclosure, a heat exchanger 30 comprises a conduit 32 in which are defined a generally round central passageway 36 and, in this embodiment, three radially outer arc-shaped fluid paths 38. Each of these can extend more than 90 degrees around the circumference of the central fluid path. Disposed on an outer periphery 42 of the conduit 32 is a heating element 46. While the conduits in this embodiment and several other embodiments are illustrated as being generally identical to each other in cross section, this does not need to be so. Rather, the conduits could have different shapes in cross section if that is considered advantageous for a particular heat transfer environment. In addition, in one embodiment, the fluid passages can be regular in cross section along the longitudinal axis of the conduit body. However, it should be appreciated that in some embodiments, the passages could vary in cross section along the longitudinal axis of a conduit body. This may be necessary for certain heat transfer applications. One process for constructing a conduit having fluid passages which are irregular in cross section is via 3D printing.

With reference now to FIG. 3, according to still another embodiment of the present disclosure, there is provided a heat exchanger 50. In this embodiment, the heat exchanger comprises a conduit 52 which is polygonal in cross section. More particularly, the conduit is generally hexagonal in cross section. Extending longitudinally or axially through the conduit 52 is a central passageway 56. In this embodiment, the central passageway 56 is also generally hexagonal in cross section. Located radially around the central passageway 56 are a plurality of fluid paths 58, each of which is generally elliptical or oval in cross section. In this embodiment, six such passageways or paths are provided. Located on an outer periphery 62 of the conduit 52 are one or more heat transfer elements 66. In this embodiment, the heat transfer elements can be flat temperature control elements, such as PTC thermistors or Peltier elements.

Peltier elements, which are sometimes known as thermoelectric coolers, allow for a substantial amount of heat transfer between the hot side of the device and the cold side thereof. In essence, a Peltier device is a small active heat pump. The Peltier effect is used to create a heat flux. One advantage of a Peltier device is that the heating and cooling sides of the element can be reversed simply by changing the orientation of the current flow. Thus, in one orientation of current flow, the cool side is on the bottom surface of the device which is in contact with the outer periphery 62 of the conduit 52, whereas a current flow in the opposite orientation will put the hot side of the device in contact with the outer periphery of the conduit. Thus, a Peltier device can be used either for heating or for cooling, although in practice, the main application is cooling. Hence, another name for a Peltier element is thermo-electric cooler (TEC). One could employ a different heat transfer device such as a PTC thermistor for heating.

If desired, resistance wire could also be used in the configuration of FIG. 3. Six is an ideal number so that the heating elements 66 could be wired either as single phase or three phases. However, other configurations (such as four, eight, ten or twelve) could also work for this type of system. In order to increase the efficiency of the heat exchanger, the fluid paths can be oriented directly parallel to the flat surfaces of the thermal transfer conduit 52.

With reference now to FIG. 4, according to yet another embodiment of the present disclosure, there is provided a heat exchanger 70 comprising a conduit 72 which can be generally cylindrical in shape. The conduit includes a central passageway 76 around which are radially arranged one or more fluid paths 78. In this embodiment, the central passageway 76 can be circular, whereas the surrounding fluid paths 78 can be oval and somewhat teardrop or egg-shaped. It should be appreciated that the length of the conduit 72 can be any desired length as may be required for a particular heat transfer application. Located on an outer periphery 82 of the conduit 72 can be a heating element (not shown). In this embodiment, the central passageway 76 can be used either as a heating passage or as a cooling passage for the several fluid paths 78 extending radially around the central passageway 76. Thus, in this embodiment, both the heating element and the central passageway 76 (via a known cartridge heater) could be employed to heat the process fluid which passes through the several fluid paths 78.

In another embodiment, only the heating element provides heat to the fluid flowing through the fluid path 78, while the central passageway provides a cooling fluid path in order to regulate the heat transfer to the process fluid flowing in the fluid paths 78. Thus, in this embodiment, both heating and cooling are integrated directly into one device. While heating can be provided on the outer periphery of the conduit 72, additional heating or cooling could be channeled through the central pathway or central passage 76. In the case where the central passageway 76 is used for cooling, then both heating and cooling could take place independently or at the same time in the heat exchanger 70 in order to control or regulate the temperature of the process fluid passing through the fluid paths 78, to within a range of 1° C. or less and perhaps as closely as a range of 0.1° C. or less.

In another embodiment, and with reference now to FIG. 5, a heat exchanger 90 includes a conduit 92 which can be generally round in cross section. The conduit 92 includes a central passageway 96 which, in this embodiment, is circular in cross section, as well as several radially located fluid paths 98 which can be oval, egg-shaped or teardrop-shaped in this embodiment. Located on an outer periphery 102 of the conduit can be one or more heating elements (not shown). While the heating elements can heat the conduit 92 as the fluid to be thermally treated passes through the fluid paths 98, the central passageway or bore 96 can provide thermal transfer either by provision of a known cartridge heater or passing a heating fluid or a cooling fluid through the central passageway 96. As with the embodiment of FIG. 4, the length of the conduit 92 can be any desired length as may be required for a particular heat transfer application.

With reference now to FIGS. 6A-6C, several configurations of end caps are there illustrated. In the configuration of FIG. 6A, an end cap includes a conduit 110 which can connect to the tube or conduit, including the several flow paths illustrated in any of the embodiments discussed so far. The conduit 110 has a port 112 which connects to an end of the heat exchanger. The port 112 can be an inlet port or an outlet port as desired. The conduit 110 is mated with an end cap 116 in which there are provided one or more baffles 118.

In another embodiment, as illustrated in FIG. 6B, there are provided two conduits 110′ and 111 which can connect to two different heat exchanger tubes or conduits. Thus, in this embodiment, one conduit 110′ could serve as one of an inlet port or outlet port of the heat exchanger as desired and the other conduit 111 could serve as the other of the outlet port and inlet port for the end cap 116′. Provided in the end cap are one or more baffles 118′. It should be apparent that in the embodiment of FIGS. 6B, the baffles are not equally located so that the several pads 119 illustrated are of different sizes.

With reference now to FIG. 6C, yet another end cap 116″ is there illustrated. In this end cap, there are provided several baffles 118′. The end cap 116′ can be positioned on the opposite end of the tube or conduit to which an end cap similar to the one shown in FIG. 6B, i.e., having both an inlet conduit and an outlet conduit, is mounted.

Depending on the application, it is known that turbulent flow is better than laminar flow. Therefore, in order to increase flow velocities within each tube, all of the fluid pathways could be connected in series. If fluid flow is high and pressure drop is a concern, on the other hand, all of the fluid pathways could be connected in parallel. The end cap 116 is used to manifold the ends of the heat exchanger and is designed in such a way so as to permit changing the flow of fluid through the heat exchanger by the design of the manifold. This could be achieved either by machining, molding or through adding baffles, such as at 118, to the inside of the cap 116 prior to final assembly of the manifold. This allows the heat exchanger to operate at maximum efficiency based upon the specific application.

The heat exchanger can, thus, comprise a plurality or multiple of parallel fluid flow paths. In the several embodiments discussed hereinbefore, the fluid flow paths form a radial array. For use in very high flow recirculation applications, all of the fluid flow paths could be allowed to flow in parallel to minimize pressure drop. In the case of a low flow single pass application, the several fluid paths could be operated in series in order to insure adequate fluid velocity through each tube and thus maintain good heat transfer. Thus, the fluid flow could be similarly divided into two, three, four, six or more parallel paths which are “tuned” to the specific application.

With reference now to FIG. 7, there is provided a heat exchanger 120 which includes a conduit 122. Extending axially in the conduit is a central passageway 126. Extending radially around the central passageway 126 is a plurality of peripheral flow passageways 128. In this embodiment, the central passageway 126 is generally circular in cross section, whereas the peripheral passageways or paths 128 are generally hexagonal in cross section. It should be appreciated that the passageways in numerous embodiments can in cross section be circular, elliptical or polygonal as desired or required for a particular application. Similarly, a cross section of the conduit itself can be circular, elliptical or polygonal, not only in this embodiment, but in numerous embodiments. Located on an outer periphery 132 of the conduit are a plurality of heating elements 136.

With reference now to FIG. 8, there is provided a heat exchanger 140 which comprises a conduit 142. Extending axially through the conduit is a central passageway 146. Located radially around the central passageway 146 are a plurality of flow paths 148. In this embodiment, eight such elliptical or oval (in cross section) flow paths are provided. Of course, any desired number can be provided. However, the central passageway can be circular in cross section if so desired. Located on an outer periphery 152 of the conduit 142 is a heating element 156. In this embodiment, the heating element comprises an electrical resistance heating wire. As illustrated in the embodiment of FIG. 8, one or more of the flow paths 148 can be lined with a chemically resistive layer 158 such as, for example, a layer of a fluoropolymer which can resist the highly corrosive fluids that are meant to be heated or cooled in the conduit. Such layers or coatings can be applied via deposition of the coating onto the walls of the passageway. It would also be advantageous that the coating material, in addition to being resistant to a range of corrosive fluids, also not be electrically conductive and be a relatively efficient conductor of heat. Polytetrafluoroethylene (PTFE) and certain ceramic materials, such as alumina would be suitable for this purpose. Alternatively for flammable fluids, the coating material can be electrically conductive in order to provide a ground plane. For example, a carbon based material which is also chemically resistive would be suitable for this purpose. Also, while an electrical resistance heating wire can be employed as the heating element 156, another type of heating element that could be employed would be a printed resistance heater which is directly applied or bonded to the outer surface or periphery 152 of the conduit 142.

Located in the central passageways 126 and 146 in at least one of the embodiments shown in FIGS. 7 and 8 can be a cartridge style heater 159 (FIG. 8) as is known in the art. Therefore, in the embodiments of FIGS. 7 and 8, heat transfer is provided both by the outer heating elements 136 and 156 and by the centrally located heater cartridge. In this way, the fluid passing through the peripheral flow passages 128 and 148 is heated both from the radially inner side of the flow passages 128 and 148 and from the radially outer side thereof.

With reference now to FIG. 9, in another embodiment of a heat exchanger 160 according to the present embodiment, the heat exchanger includes a conduit 162 which is provided with a central passageway 166 and a plurality of radially arrayed passageways 168 surrounding the central passageway. In this embodiment, both the central passageway and the peripheral passageways are circular in cross section.

In another embodiment of the present disclosure and with reference to FIG. 10, there is provided a heat exchanger 180 which comprises a conduit 182 that is provided with a central passageway 186 and four radially arrayed or peripherally located passageways 188. In this embodiment, while the central passageway 186 is circular in cross section, the peripheral passageways 188 are oval or elliptical in cross section.

In a yet further embodiment of the present disclosure, there is provided a heat exchanger 190, as shown in FIG. 11, which comprises a conduit 192 that is provided with a plurality of spaced passageways 194. In this embodiment, there is no central passageway. Rather, there are four spaced generally elliptical or oval passageways 194 extending from a first end of the conduit 192 to a second end thereof. Thus, it is conceivable to provide a unitary one-piece conduit or tube which does not have a central passageway, but rather has a plurality of equally sized, or unequally sized, passages or passageways of any desired particular cross section for use as a heat exchanger for process fluids flowing through the conduit.

With reference now to FIG. 12, there is disclosed a still yet further embodiment of the present disclosure. In this embodiment, a heat exchanger 200 comprises a conduit 202 in which are defined spaced first and second passageways 206 and 208. With reference now also to FIG. 13, the passageways can extend from a first end 230 of the conduit 202 to a second end 232 of the conduit. In this embodiment, the passageways are of generally the same size and shape, although other configurations are also contemplated. The two passageways 206 and 208 are separated from each other by a wall 210. In this embodiment, the wall 210 extends along a longitudinal axis of the conduit 202 from the first end of the conduit to a second end thereof. In this way, the wall separates the two passageways 206 and 208 from each other along the length of the conduit 202. In one embodiment, each of the passageways 206 and 208 includes a peripheral wall which is defined by a set of spaced ribs 214 and grooves 216. It is believed that the provision of such ribs and grooves will improve heat transfer from a heater member 240 to a fluid (again, that fluid can be a liquid or a gas) flowing through the passageways 206 and 208. The heater member 240 can be a resistance heating element or a printed heater that is directly applied or bonded to an outer surface 242 of the conduit 202. The heat exchanger embodiment of FIGS. 12 and 13 may be particularly advantageous for heat transfer to one or more gases flowing through the passageways 206 and 208. Of course, more than two passageways or passages can be provided if so desired.

With reference now to FIG. 14, a point of dispense heat exchanger 300 according to a yet further embodiment of the present disclosure comprises a unitary one-piece conduit or tube 302. Defined in the conduit is a central passageway 310 and positioned radially outwardly therefrom are a plurality of spaced fluid paths 312. In this embodiment, the central passageway 310 can be hexagonal in cross section, whereas the several fluid paths 312 can be teardrop-shaped or egg-shaped or elliptical with their smaller radius ends pointing towards the central passageway and their larger radius ends pointing towards an outer periphery 314 of the conduit 302. In this embodiment, defined between each of the several fluid paths 312 are slots 320 which extend inwardly from the periphery 314 towards the central passageway 310, but stop short of the central passageway. Positioned in these slots can be heating elements such as PTC heaters or chips 330. For each of these heater elements, a first face 332 is located adjacent a first one of the fluid paths 312, whereas a second face 334 is located adjacent a second one of the fluid paths 312. In this way, both of the heat conducting faces of each of the heater elements 330 are located adjacent one of the fluid paths 312. It can be seen that each of the fluid paths 312 is thus heated from both sides by a respective heater element face.

Electrically contacting the respective faces 332 and 334 of the PTC chips 330 are a pair of electrodes 340 and 342. The electrodes are illustrated as being somewhat corrugated in an end view. However, the electrodes could take different shapes if so desired. The electrodes can be of any desired length. If desired, positioned between the electrodes and the PTC heaters or chips 330 can be a known electrically conductive and stress relieving interface pad, film or coating (not illustrated) for contacting the opposed faces 332 and 334 of each PTC element. As is known, such interface pads can be constructed of a graphite film or compound which would provide good electrical and heat transfer from the PTC elements when they are energized, both to the electrodes and to the adjacent walls of the conduit or tube 302. In that way, the heat from the PTC elements or chips can be transmitted via conduction through the walls surrounding the several fluid paths 312 to a fluid flowing through the fluid paths and perhaps also a fluid flowing through the central passageway 310, if so desired.

The several fluid paths 312 are located radially outwardly of the central passageway or bore 310 and there is no fluid communication between the central passageway 310 and the several fluid paths 312. Moreover, the several fluid paths 312 also do not communicate with each other. Rather, all of these extend generally parallel to each other and parallel to the central fluid path 310 and extend along an axis of the conduit 302 from a first end thereof to a second end thereof. Thus, a fluid flowing in the several fluid paths 312 does not mix with a fluid flowing in any of the other fluid paths, nor with a potential fluid flowing through the central passageway 310. On the other hand, the central passageway can be employed to house a heater cartridge, if desired. Alternatively, the central passageway can be employed to conduct either a heating fluid or a cooling fluid as may be desired or required for a particular fluid processing technique.

In this embodiment, the singular or unitary or one-piece conduit or tube 302 serves as the interface between fluid paths and heating or cooling sources. The conduit can be configured to accommodate a broad range of fluids for a variety of applications. Moreover, the conduit can be made from a range of materials that can be selected in order to provide optimum heat transfer and chemical compatibility.

With reference now to FIG. 15, illustrated schematically is a dispensing nozzle 400 used, for example, in semiconductor manufacturing. The nozzle 400 includes a first conduit section 402, a second conduit section 404, that can be disposed at a right angle to the first conduit section, and a tip section 406. Any of the various heat transfer or thermal transfer assemblies illustrated in the several embodiments of the instant disclosure can be located in such nozzle 400. In one embodiment, the location can be as at 410 in the first conduit section 402. In another embodiment, the location can be as at 420 in the second conduit section 404.

In both embodiments, the conventional fluid recirculation loop is eliminated by placing the process fluid heat exchanger as close to the processing fluid nozzle tip 406 as possible. This creates a point of dispense heat exchanger and allows the processing fluid to remain at ambient temperatures while it is conducted to the nozzle. The process fluid is only heated or cooled at the nozzle, near the tip 406, as required for the processing temperature needed for that fluid directly at the point where the semiconductor wafer is processed. Such a construction serves to minimize the foot print of the processing fluid handling and preprocessing preparation section of the plumbing area of the semiconductor tool. Moreover, the processing fluid is, thus, no longer subjected to the same types of temperature losses as currently occurs when the fluid transfers from a heated tank of the fluid to the processing area. In addition, the amount of processing fluids can be reduced with the heat exchanger assembly illustrated herein and, hence, the cost of employing such processing fluids can also be reduced. It is also potentially possible to increase the yield of each semiconductor manufacturing tool by installing the heat exchanger inside the nozzle, as better control of the temperature of the processing fluid can be obtained. With better temperature control, identical etch rates can be obtained across an entire semiconductor wafer even if multiple nozzles are used. The construction illustrated in FIG. 15, thus, greatly simplifies the cost and configuration of processing tools and enhances their functionality.

It should be appreciated that multiple nozzles can be employed simultaneously to dispense one or more types of processing fluids at different temperatures across the width of a wafer so that the yield from a wafer can be increased. Even the periphery of the wafer can be subjected to the same etch rates as is the center of the wafer.

The instant disclosure addresses the several mentioned aspects of heat exchange to allow for an efficient, effective, and controllable point of dispense heat exchanger. A heat exchanger material which is compatible with nearly all semiconductor wet processing fluids is single crystal aluminum oxide or sapphire. As mentioned, sapphire has very good thermal transfer properties, but only in the direction of the crystal. This is optimum for constructing a fluid containment device allowing very low mass and directional heat transfer. Creating a flow path through the sapphire with a plurality of conduits having oval or elliptical or other cross sectional shapes allows for a maximum heat transfer area and figure of merit by sizing the oval, elliptical or other shapes of the cross sections of the conduits based upon desired flow rate, temperature rise and viscosity. By applying the heat source directly on the outside of the conduit or tube or within the periphery of the conduit or tube (see FIG. 14), a very low thermal mass is then obtained for the heat transfer device. A compact heat exchanger having a large surface area and a small mass is desirable as noted above. With such a heat exchanger, much better heat conduction is possible and the fluid being heated or cooled can perhaps even remain more pure than with conventional heat exchangers.

As mentioned, for some semiconductor processing or treatment fluids, other conduit materials including various metals such as stainless steel or titanium, a vitreous carbon material or quartz could also be used. Each of these materials would allow for a lower cost alternative to sapphire. But, such alternative materials may not be useable for all of the types of processing fluids required in semiconductor wafer processing. The several embodiments of configurable flow paths discussed above, however, would allow these other materials to be used in many process applications, particularly if one or more flow paths are coated with a layer of a fluoropolymer or other chemically inert material.

While it has been discussed that the elongated one-piece unitary conduit body can be made of or grown as a single crystal, it should be appreciated that there are other potential ways of manufacturing such a unitary one-piece tubular fluid conduit. For example, one could manufacture such a tubular fluid conduit by employing newly developed 3D printers which are capable of using several of the materials mentioned herein. Thus, additive manufacturing or 3D printing and manufacturing may be employed advantageously to produce or create such unitary one-piece tubular fluid conduits having more than one fluid passage therein.

It should also be appreciated that while the inline heat exchangers described herein are discussed in the context of heaters for semiconductor wafer processing, the heat exchangers clearly have a multitude of other uses in that they can be used for heating or cooling of various types of fluids, both liquid and gas, in a variety of other environments as well.

According to one embodiment of the present disclosure, there is provided a one-piece or unitary heat exchanger comprising a conduit including at least two spaced passageways. The at least two passageways extend generally parallel to each other in the conduit. They extend axially from a first end of the conduit to a second end of the conduit and do not communicate with each other. Also provided is a heat transfer element which thermally contacts a surface of the conduit.

The present disclosure has been described with reference to the several embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the instant disclosure be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof. 

1. A point of dispense heat exchanger assembly comprising: an elongated conduit body including: a first end, a second end, an outer periphery, a first fluid passage defined in the conduit body and extending longitudinally in the conduit body from the first end thereof to the second end thereof, a second fluid passage defined in the conduit body and extending longitudinally in the conduit body from the first end thereof to the second end thereof, wherein the second fluid passage is spaced from and fluidically isolated from the first fluid passage; and, a heat transfer element mounted to the outer periphery of the conduit body, wherein the heat transfer element thermally contacts the conduit body and is adapted to transfer heat to or from the conduit body by conduction.
 2. The assembly of claim 1 wherein the conduit body is unitary and of one-piece and comprises a single crystal.
 3. The assembly of claim 2 wherein the single crystal comprises sapphire.
 4. The assembly of claim 1 wherein the heat transfer element comprises at least one of an electrical resistance heater cable mounted to the conduit body, a positive temperature coefficient (PTC) electrical heating element mounted to the conduit body, and a Peltier element mounted to the conduit body.
 5. The assembly of claim 1 further comprising one of an electric cartridge heater located in a longitudinally extending central bore defined in the conduit body, or a cooling fluid flowing through the central bore.
 6. The assembly of claim 1 wherein the conduit body includes a plurality of spaced fluid passages and a plurality of slots, wherein the heat transfer element comprises a PTC heating element and each slot accommodates a PTC heating element wherein each PTC heating element is located between two of the plurality of fluid passages.
 7. The assembly of claim 1 wherein the conduit body is made of an electrically non-conducting material.
 8. The assembly of claim 1 wherein the first and second fluid passages are non-circular in cross-section so as to promote a turbulent flow of a process fluid.
 9. The assembly of claim 8 wherein the first and second fluid passages are one of elliptical, oval and polygonal in cross section.
 10. The assembly of claim 9 wherein the first and second fluid passages are regular in cross section along a longitudinal axis of the conduit body.
 11. The assembly of claim 1 wherein the conduit body is one of circular and polygonal in cross section.
 12. The assembly of claim 1 further comprising a layer of a chemically inert material coating a surface of at least one of the first fluid passage and the second fluid passage.
 13. The assembly of claim 12 wherein the coating material is one of an electrically insulative material, and an electrically conductive material.
 14. The assembly of claim 1 wherein the first and second fluid passages extend generally parallel to each other.
 15. A method of controlling heat transfer to a process fluid flowing in a conduit disposed in a nozzle, comprising: providing a conduit body including a first end, a second end, an outer periphery and a longitudinal axis; defining a central bore in the conduit body, the central bore extending along the longitudinal axis from the first end of the conduit body to the second end thereof; defining a first process fluid passage in the conduit body, the first process fluid passage extending parallel to the longitudinal axis from the first end of the conduit body to the second end thereof; defining a second process fluid passage in the conduit body, the second process fluid passage extending parallel to the longitudinal axis from the first end of the conduit body to the second end thereof wherein the first and second process fluid passages are fluidically isolated from each other and the central bore; thermally contacting the outer periphery of the conduit body with a first heat transfer source; thermally contacting the central bore of the conduit body with a second heat transfer source; and regulating a transfer of heat to the process fluid flowing through the first and second fluid passages.
 16. The method of claim 15 wherein the first heat transfer source comprises at least one of an electrical resistance heater cable, a positive temperature coefficient (PTC) heating element and a Peltier element.
 17. The method of claim 15 wherein the second heat transfer element comprises an electric cartridge heater positioned in the central bore or a cooling fluid flowing through the central bore.
 18. The method of claim 15 wherein a temperature of the process fluid is regulated to within a range of less than 1° C.
 19. The method of claim 15 further comprising the step of causing a turbulent flow of the process fluid through the first and second fluid passages.
 20. A unitary, one-piece tubular fluid conduit for a point of dispense heat exchanger, comprising: a first end; a second end; an outer periphery; a longitudinal axis; a first process fluid passage defined in the conduit and extending in the conduit parallel to the longitudinal axis from the first end thereof to the second end thereof; a second process fluid passage defined in the conduit and extending in the conduit parallel to the longitudinal axis from the first end thereof to the second end thereof; a central bore defined in the conduit and extending along the longitudinal axis, wherein the first and second fluid passages are located radially outward of the central bore; and wherein the first and second process fluid passages are non-circular in cross section to promote a turbulent flow of the process fluid.
 21. The conduit of claim 20 wherein the first and second process fluid passages and the central bore are fluidically isolated from each other.
 22. The conduit of claim 20 wherein the tubular conduit further comprises a thermally conductive and electrically isolating material.
 23. The conduit of claim 20 wherein the tubular conduit comprises a single crystal.
 24. The conduit of claim 23 wherein the single crystal is sapphire.
 25. The conduit of claim 20 wherein the first and second fluid passages are elliptical or oval in cross section. 